PPP2R1B

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Protein-coding gene in the species Homo sapiens

title: "PPP2R1B" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public description: "Protein-coding gene in the species Homo sapiens" topic_path: "uncategorized" source: "https://en.wikipedia.org/wiki/PPP2R1B" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0

::summary Protein-coding gene in the species Homo sapiens ::

Serine/threonine-protein phosphatase 2A 65 kDa regulatory subunit A beta isoform is an enzyme that in humans is encoded by the PPP2R1B gene.

Function

This gene encodes a constant regulatory subunit of protein phosphatase 2. Protein phosphatase 2 is one of the four major Ser/Thr phosphatases, and it is implicated in the negative control of cell growth and division. It consists of a common heteromeric core enzyme, which is composed of a catalytic subunit and a constant regulatory subunit, that associates with a variety of regulatory subunits. The constant regulatory subunit A serves as a scaffolding molecule to coordinate the assembly of the catalytic subunit and a variable regulatory B subunit. This gene encodes a beta isoform of the constant regulatory subunit A. Defects in this gene could be the cause of some lung and colon cancers. At least two transcript variants encoding different isoforms have been found for this gene.

Discovery

The PPP2R1B gene was discovered as part of the Human Genome Project research center focused on chromosome 11.

Clinical significance

Somatic alterations in PPP2R1B have been identified in colorectal and lung cancer tumors and cell lines, with evidence that these alterations affect protein function, supporting a role for PPP2R1B as a candidate tumor suppressor gene in these cancers. Experimental studies have shown that suppression of PPP2R1B expression enables immortalized human cells to become tumorigenic, and that the wild-type protein forms a complex with the small GTPase RalA. These findings support the role of PPP2R1B as a tumor suppressor involved in regulating RalA function.

A case series described nine cancer patients with germline loss-of-function (LOF) variants in PPP2R1B, with breast cancer being the most frequently observed diagnosis. In all documented cases, individuals also had a family history of cancers including breast, ovarian, prostate, uterine, renal, and colorectal cancer, suggesting that PPP2R1B may function as a predisposition gene in breast and potentially other cancers.

Interactions

PPP2R1B has been shown to interact with:

References

References

  1. (April 1990). "alpha- and beta-forms of the 65-kDa subunit of protein phosphatase 2A have a similar 39 amino acid repeating structure". Biochemistry.
  2. (September 1998). "Genomic organization and precise physical location of protein phosphatase 2A regulatory subunit A beta isoform gene on chromosome band 11q23". Gene.
  3. "Entrez Gene: PPP2R1B protein phosphatase 2 (formerly 2A), regulatory subunit A, beta isoform".
  4. (October 1998). "Alterations of the PPP2R1B gene in human lung and colon cancer". Science.
  5. "PPP2R1B is a tumor suppressor".
  6. (June 2007). "The tumor suppressor PP2A Abeta regulates the RalA GTPase". Cell.
  7. (April 2025). "Germline loss-of-function mutations in PPP2R1B in patients with a personal and family history of cancer". JCI Insight.
  8. (October 1992). "Expression of the A subunit of protein phosphatase 2A and characterization of its interactions with the catalytic and regulatory subunits". The Journal of Biological Chemistry.
  9. (January 2003). "Characterization of the Aalpha and Abeta subunit isoforms of protein phosphatase 2A: differences in expression, subunit interaction, and evolution". The Biochemical Journal.
  10. (September 1996). "The B56 family of protein phosphatase 2A (PP2A) regulatory subunits encodes differentiation-induced phosphoproteins that target PP2A to both nucleus and cytoplasm". The Journal of Biological Chemistry.

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